Ropinirole is provided as oral preparations in the form of hydrochloric acid addition salts, and used for the treatment of Parkinson's disease. Patent Literatures 1 and 2 each describe the inventions relating to the production processes of ropinirole as a drug substance and high purity ropinirole hydrochloride as a drug substance. Also, transdermal preparations containing ropinirole are disclosed in, for example, Patent Literatures 3 and 4. Patent Literature 5 describes that, in a transdermal drug delivery system, the liquid body and the basic form of low-molecular weight drugs exhibits excessive plasticizing effects on a polymer.
Meanwhile, 4-ethylene-2(3H)-indolone having the following molecular structure (alternative name: 4-ethylenyl-1,3-dihydro-2H-indol-2-one. Hereinbelow, this compound may be abbreviated as “4E indolone”) is given a CAS No. 120427-93-2, and known as a decomposition product of ropinirole N-oxide.
